let me give you a typical example of where I routinely use tables in a form.
In a customised cms for a newsletter subscription website I will have a menu item called "Manage Users".
When I extract the users' records from the database and display them in a form I will have going across the page for each user record columns titled
userID, first name, last name, email, subscriptions, access level, edit, delete
The edit will be a link to a "user info" form and the delete will be a checkbox so I can delet multiple users in 1 go, but that is beside the point.
Imho these rows of users x 8 columns can legitimately be argued to be tabular data and so it is legitimate to use a table to display these rows and columns in a table within a <form>.
The table cells can still containg <labels> and other appropriate elements where required but in terms of aligning x number of rows by 8 columns correctly a table is much quicker and simpler for me.
If you accept the above as being valid then it makes no difference whether the data has 2,3,4 or whatever number of columns.
I agree that "generally speaking" tables are a no-no for content layout but as I say above, imho the above type of data can be argued to be tabular data.
The defence rests its case your honour